C# .BigMul()

The Math.BigMul() method multiplies two integer values and returns the full extended result to avoid overflow. It ensures that the product fits within a larger data type when the operands are 32-bit or 64-bit integers.

Syntax

Math.BigMul(x, y);

Parameters:

• x, y: The integers to be multiplied. These can be of type int, uint, long, or ulong.

Return value:

Returns the full product of x and y as a single 64-bit or 128-bit integer, depending on the input type:

• If x and y are of type int or uint, the return type is long and ulong, respectively.
• If x and y are of type long or ulong, the return type is Int128 and UInt128, respectively.

Note: The Int128 and UInt128 types were introduced in .NET 7. In earlier versions, Math.BigMul(long, long, out long high) can be used to obtain the high and low 64-bit parts of the product.

Example: Basic Usage

In this example, the full product of two int values is calculated without overflow:

using System;

public class Example {
  public static void Main() {
    // Integer values (32-bit)
    int intX = 100000;
    int intY = 500000;

    // Compute the product safely
    long intResult = Math.BigMul(intX, intY);

    Console.WriteLine($"Math.BigMul({intX}, {intY}) = {intResult}");
  }
}

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This example outputs the following:

Math.BigMul(100000, 500000) = 50000000000

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Codebyte Example

The following example demonstrates the use of Math.BigMul() to calculate the product of two integers that would normally cause an overflow with standard multiplication:

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